Antarctic red algae in dye-sensitized photoelectrochemical cells for water splitting

Phycoerythrin extracted from Antarctic red seaweeds shows promising characteristics to be applied as an anode sensitizer in water-splitting photoelectrochemical cells.Under light irradiation and using an LED lamp,the red-colored protein shows an interesting ability to profit the incident light,as confirmed by the presence of oxygen bubbles next to the electrode surface without applying any external potential.Our results showed that the addition of iodide is helpful to allow the regeneration of the dye;nevertheless,oxygen evolution is not favored.Thermodynamics analysis of the involved semi-reactions is also helpful to understand the observed results.The exploration of Antarctic resources offers then an alternative for the development of green energies,with a particular focus on their use as sensitizers to profit from the sunlight in water-splitting as well as in photovoltaic devices.

Phylogenomic analysis of transcriptomic sequences of mitochondria and chloroplasts for marine red algae(Rhodophyta)in China

The chloroplast and mitochondrion of red algae （Phylum Rhodophyta） may have originated from different endosymbiosis. In this study, we carried out phylogenomic analysis to distinguish their evolutionary lin-eages by using red algal RNA-seq datasets of the 1 000 Plants （1KP） Project and publicly available complete genomes of mitochondria and chloroplasts of Rhodophyta. We have found that red algae were divided into three clades of orders, Florideophyceae, Bangiophyceae and Cyanidiophyceae. Taxonomy resolution for Class Florideophyceae showed that Order Gigartinales was close to Order Halymeniales, while Order Graci-lariales was in a clade of Order Ceramials. We confirmed Prionitis divaricata （Family Halymeniaceae） was closely related to the clade of Order Gracilariales, rather than to genus Grateloupia of Order Halymeniales as reported before. Furthermore, we found both mitochondrial and chloroplastic genes in Rhodophyta under negative selection （Ka/Ks〈1）, suggesting that red algae, as one primitive group of eukaryotic algae, might share joint evolutionary history with these two organelles for a long time, although we identified some dif-ferences in their phylogenetic trees. Our analysis provided the basic phylogenetic relationships of red algae, and demonstrated their potential ability to study endosymbiotic events.

Metabolic relationships between marine red algae and algae‑associated bacteria

Mutualistic interactions between marine phototrophs and associated bacteria are an important strategy for their success-ful survival in the ocean,but little is known about their metabolic relationships.Here,bacterial communities in the algal sphere(AS)and bulk solution(BS)of nine marine red algal cultures were analyzed,and Roseibium and Phycisphaera were identified significantly more abundantly in AS than in BS.The metabolic features of Roseibium RMAR6-6(isolated and genome-sequenced),Phycisphaera MAG 12(obtained by metagenomic sequencing),and a marine red alga,Porphyridium purpureum CCMP1328(from GenBank),were analyzed bioinformatically.RMAR6-6 has the genetic capability to fix nitrogen and produce B vitamins(B1,B2,B5,B6,B9,and B12),bacterioferritin,dimethylsulfoniopropionate(DMSP),and phenylacetate that may enhance algal growth,whereas MAG 12 may have a limited metabolic capability,not producing vitamins B9 and B12,DMSP,phenylacetate,and siderophores,but with the ability to produce bacitracin,possibly modulating algal microbiome.P.purpureum CCMP1328 lacks the genetic capability to fix nitrogen and produce vitamin B12,DMSP,phenylacetate,and siderophore.It was shown that the nitrogen-fixing ability of RMAR6-6 promoted the growth of P.pur-pureum,and DMSP reduced the oxidative stress of P.purpureum.The metabolic interactions between strain RMAR6-6 and P.purpureum CCMP1328 were also investigated by the transcriptomic analyses of their monoculture and co-culture.Taken together,potential metabolic relationships between Roseibium and P.purpureum were proposed.This study provides a bet-ter understanding of the metabolic relationships between marine algae and algae-associated bacteria for successful growth.

The P450-type carotene hydroxylase PuCHY1 from Porphyra suggests the evolution of carotenoid metabolism in red algae

Carotene hydroxylases catalyze the hydroxylation of a- and β-carotene hydrocarbons into xanthophylls.In red algae,β-carotene is a ubiquitously distributed carotenoid,and hydroxylated carotenoids such as zeaxanthin and lutein are also found.However,no enzyme with carotene hydroxylase activity had been previously identified in red algae.Here,we report the isolation of a gene encoding a cytochrome P450-type carotene hydroxylase（PuCHY1） from Porphyra umbilicalis,a red alga with an ancient origin.Sequence comparisons found PuCHY1 belongs to the CYP97 B subfamily,which has members from different photosynthetic organisms ranging from red algae to land plants.Functional complementation in Escherichia coli suggested that PuCHY1 catalyzed the conversion from β-carotene to zeaxanthin.When we overexpressed PuCHYi in the Arabidopsis thaliana chy2 mutant,pigment analysis showed a significant accumulation of hydroxylated carotenoids,including neoxanthin,violaxanthin,and lutein in the leaves of transgenic plants.These results confirmed a β-hydroxylation activity of PuCHY1,and also suggested a possible ε-hydroxylation function.The pigment profile and gene expression analyses of the algal thallus under high-light stress suggested that P.umbilicalis is unlikely to operate a partial xanthophyll cycle for photoprotection.

Hepatoprotective efficiency of methanol extract of red algae against chromium-induced oxidative damage in Wistar rats

Objective:To investigate the hepatoprotective activity of red algae Portieria hornemannii(Lyngbye)Silva(P.hornemannii)and Spyridia fusiformis Boergesen(S.fusiformis)by using the chromium treated rat liver as the animal model.Methods:The extract of red algae at a dosage of 0.200 g/kg of whole body weight was orally administrated to Cr(VI)intoxicated rats for 28 consecutive days.The effect of drug in rats was evaluated by comparing the degree of the production of enzymes responsible for antioxidant activity such lipid peroxidase,superoxide dismutase,catalase and reduced glutathione with Cr(VI)analogs in the absence of any secondary treatment.The overall damage of liver was detected by measuring serum enzymes such as aspartate amino transferase and alanine aminotransferase activities which released into the blood from the damaged cells.Results:It was observed that these enzyme levels were noticed in the animals treated with methanol extracts of red algae(200 mg/kg)through preventing the leakage of the above enzymes into the blood.The hepatoprotection obtained using LIV 52(standard reference drug)appeared relatively higher.The antihepatotoxic potential of red algae P.hornemannii and S.fusiformis might be due to their antioxidative and membrane stabilizing activities.Conclusions:Our results indicated that the extract of P.hornemannii and S.fusiformis obtained from methanol could be a promising hepatoprotective agent against chromium(VI)-induced liver damage.

In vitro cytotoxic studies of red algae Portieria hornemannii and Spyridia fusiformis against Dalton’s lymphoma ascite and Ehrlich ascite carcinoma cell lines

Objective:To study the in vitro cytotoxic activities of methanol extract of Portieria hornemannii(P.hornemannii)and Spyridia fusiformis(S.fusiformis)using Dalton’s lymphoma ascite and Ehrlich ascite carcinoma cell lines.Methods:The effect of cytotoxicity of P.hornemannii and S.fusiformis was evaluated with the concentrations(100 to 200μg/mL)and assessed for the antitumour activity vs.the selected cell lines using Trypan blue assay.Results:The methanol extracts of P.hornemannii and S.fusiformis showed potent cytotoxic activity with IC_(50)values of(209.00±0.05)μg/mL and(190.00±0.05)μg/mL against the Dalton’s lymphoma ascite cell line and IC_(50)values of(190.00±0.05)μg/mL and(182.00±0.05)μg/mL against the Ehrlich ascite carcinoma cell line respectively.In vitro cytotoxicity against the tested cancer cell lines showed strong activity by the abnormal activities of algal residue in the normal cells.Conclusions:The methanol solvent residue of red algae(P.hornemannii and S.fusiformis)could be a good candidate.It would be a novel marine resource as a antitumor medicine demonstrated by cytotoxic studies that the above marine algae can be a potential candidate sources as antitumor drugs.

Phylogenetic Analysis of Epibacterial Communities on the Surfaces of Four Red Macroalgae

Macroalgal surfaces are prone to being attached by bacteria. Epibacterial community structures on marine macroalgae are host-specific but temporally and spatially variable. In this study, we investigated the structure of epibacterial communities on the surfaces of four red macroalgae, Gracilaria lemaneiformis, Gloiopeltisfurcata, Mazzaella sp. and Porphyra yezoensis, by analyzing the sequences of 16S rRNA gene libraries. Healthy individuals of all macroalgae species were collected in winter from a farm at Dalian, China. The results showed that the epibacterial communities were mainly dominated by ct-Proteobacteria, 7-Proteobacteria and Bacteroidetes. Deinococcus-Thermus, Spirochaetes and e-Proteobacteria were also found. The majority of cloned sequences shared the greatest similarity to those of culturable organisms. A large portion of sequences from the ct-Proteobacteria homed in Roseobacter clade, i.e., genera Ahrensia, Roseovarius, Litoreibacter, Octadecabacter, Thaiassobacter and Sulfitobacter, while members of Bacteroidetes mainly belonged to family Flavobacteriaceae. The cloned sequences could be separated into 66 OTUs at 0.01 distance value, and rare common OTUs were found among libraries. At genus level, Pseudoa#eromonas dominated Gr. lemaneiformis and GI. furcata libraries, accounting for 72.2% and 47.3%, respectively. Sulfitobacter dominated P. yezoensis library, accounting for 35.4%. A previously undefined cluster within Deinococcus-Thermus dominated Mazzaella sp. library, accounting for 24.6% of the all. These results indicated that a broad range of bacteria inhabited the surfaces of these macroalgae.

The chemical constituents from red alga Gymnogongrus flabelliformis Harv.

Eight compounds were isolated from red alga Gymnogongrus flabelliformis Harv. In normal phase silica gel, Sephadex LH-20 gel column chromatography, reverse phase HPLC, and recrystallization. Based on MS and ID NMR spectroscopic data, their structures were determined as： stigmast-4-en-3-one （Ⅰ）, cholest-4-en-3-one （Ⅱ）, cholesterol （m）, uracil （Ⅳ）, uridine （V）, adenosine （Ⅵ）, succinic acid （Ⅶ）, and 5-hydroxy-4-methyl-5-pentyl-2,5-dihydro-furan-2-on （Ⅷ）. All of them were obtained from this species for the first time. Cytotoxicity of these compounds was screened using standard MTT method, but all the compounds were inactive （IC50 〉 10 μg/ml）.

Transcriptome sequencing of essential marine brown and red algal species in China and its significance in algal biology and phylogeny

Most phaeophytes （brown algae） and rhodophytes （red algae） dwell exclusively in marine habitats and play important roles in marine ecology and biodiversity. Many of these brown and red algae are also important resources for industries such as food, medicine and materials due to their unique metabolisms and me-tabolites. However, many fundamental questions surrounding their origins, early diversification, taxonomy, and special metabolisms remain unsolved because of poor molecular bases in brown and red algal study. As part of the 1 000 Plant Project, the marine macroalgal transcriptomes of 19 Phaeophyceae species and 21 Rhodophyta species from China＇s coast were sequenced, covering a total of 2 phyla, 3 classes, 11 orders, and 19 families. An average of 2 Gb per sample and a total 87.3 Gb of RNA-seq raw data were generated. Approxi-mately 15 000 to 25 000 unigenes for each brown algal sample and 5 000 to 10 000 unigenes for each red algal sample were annotated and analyzed. The annotation results showed obvious differences in gene expres-sion and genome characteristics between red algae and brown algae;these differences could even be seen between multicellular and unicellular red algae. The results elucidate some fundamental questions about the phylogenetic taxonomy within phaeophytes and rhodophytes, and also reveal many novel metabolic pathways. These pathways include algal CO2 fixation and particular carbohydrate metabolisms, and related gene/gene family characteristics and evolution in brown and red algae. These findings build on known algal genetic information and significantly improve our understanding of algal biology, biodiversity, evolution, and potential utilization of these marine algae.

Two New Bromophenols from Red Alga Rhodomela confervoides

Two new bromophenols were isolated from Rhodomela confervoides. Their structrues were elucidated as 2, 2', 3-tribromo-3', 4, 4', 5-tetrahydroxy-6'-hydroxymethyldiphenylmethane and 2, 2', 3-tribromo-3', 4,4', 5-tetrahydroxy-6'-ethyloxymethyldiphenylmethane by spectroscopie methods including IR, HREIMS, 1D and 2D NMR techniques.

A New Brominated Phenylpropylaldehyde and its Dimethyl Acetal from Red Alga Rhodomela confervoides

A new brominated phenylpropylaldehyde and its dimethyl acetal together with a new natural brominated phenol were isolated from Rhodomela confervoides. Their structrues were elucidated as 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde, 2-methyl-3-(2,3-di-bromo-4,5-dihydroxyphenyl) propylaldehyde dimethyl acetal and 3-bromo-4,5-dihydroxybenzoic acid methyl ester by spectroscopic techniques including IR, HRFABMS, ID and 2DNMR experiments.

Sesquiterpenes from Red Alga Laurencia tristicha

Three naturally new sesquiterpenes named 10-hydroxyepiaplysin, 10-hydroxyaplysin and 10-hydroxybromoepiaplysin have been isolated from Laurencia tristicha. On the basis of the spectroscopic techniques their structures were elucidated as （3S, 3αR, 8βS）-（-）-2, 3, 3α, 8β3-tetra- hydro-7-bromo-3-hydroxy-3, 3α, 6,8β-tetramethyl-lH-cyclopenta[b]benzofuran, （3R, 3αR, 8βS）- （-）-2,3,3α, 8β-tetrahydro-7-bromo-3-hydroxy-3, 3α,6,8β-tetramethyl-lH-cyclopenta[b]benzofuran and （3S, 3αR, 8βS）-（-）-2, 3,3R, 8β-tetrahydro-3-hydroxy-3,3α,6,8β-tetramethyl-lH-cyclopenta[b]- benzofuran, respectively.

Human sperm motility stimulating activity of a sulfono glycolipid isolated from Sri Lankan marine red alga Gelidiella acerosa

Aim: To evaluate the sperm motility stimulating activity of a sulfono glycolipid (S-ACT-1) isolated from Gelidiellaacerosa, a Sfi Lankan marine red algae. Methods: S-ACT-I, a white amorphous powder was separated from morepolar fractions of the hexane soluble of 1:1 CH_2Cl_2/MeOH extract and subjected to ~1H, ^(13)C NMR and IR Spectroscopyafter reverse phase HPLC for identification. Effects of S-ACT-1 on human sperm motility was assessed in vitro at 10,100 and 1000μg/mL concentrations at 37℃ for 0, 5, 15, 30 and 60 min. Results: S-ACT-1 was identified as aglycolipid sulfate. The lower dose increased the sperm motility slightly, whilst the medium dose significantly increasedthe motility (P < 0.05) from 5 min of incubation reaching a peak at 15 min and the stimulant effect was sustainedthroughout the experimental period. Furthermore, the medium dose rendered 80% of the immotile viable sperm motile.In contrast, the highest dose impaired the sperm motility. The sperm stimulating activity of S-ACT-1 was dose-depen-dent and had a bell-shaped dose response curve for all the 5 incubation periods. Conclusion: S-ACT-1 of Gelidiellaacerosa is a Sulfono glycolipid. S-ACT-1 has a potent sperm motility stimulating activity in vitro and has the potentialto be developed into a sperm stimulant. (Asian J Androl 2001 Mar; 3: 27-31)

A new ketosteroid from red alga Acanthophora spicifera

A new ketosteroid, along with six known steroids, was isolated from the ethanolic extracts of red alga Acanthophora spicifera （Vahl.） Boergesen. The structures, identified using chemical and spectroscopic methods including 2D NMR, were： （1） 22-hydroxy-5α-eholest-3,6-dione, （2） 6-hydroxycholest-4-ene-3-one, （3） cholest-4-ene-3,6-dione, （4） cholest-5-ene-3β-ol, （5） 5u-cholestane-3,6-dione, （6） β-Sitosterol and （7） Saringosterol. The MTT method was used to test the cytotoxicity of the compounds against the human cancer cell lines, HCT-8, Bel-7402, BGC-823, A549 and HELA. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity against human cancer cell lines.

Two New Norisoprenoid Derivatives from the Red Alga Gymnogongrus flabelliformis

Two new norisoprenoid derivatives have been isolated from the red alga Gymnogongrus flabelliformis. Their structures were elucidated as （3R, 6R, 7E）-（＋）-3-O-phenylacetyl-4,7-megas- tigmadiene-9-one and （3R,TE）-（-）-3-O-phenylacetyl-5,7-megastigmadiene-9-one, respectively, by spectroscopic methods including HRMS, 1D and 2D NMR techniques.

RT-qPCR normalization of reference genes in different lifehistory stages of Gracilaria vermiculophylla(Rhodophyta)

The quantitative realtime polymerase chain reaction(RT-qPCR)is a powerful and sensitive method to measure expression of targeted gene but it highly relies on the use of suitable reference genes for data normalization.We evaluated the expressions of 8 housekeeping genes:18S ribosomal rDNA(18S rDNA),28S ribosomal r DNA(28S rDNA),rubisco large subunit(rbc-L),β-actin(ACT),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),elongation factor 1(EF1),β-tubulin(Tub B),and P-phycoerythrin B(PEB),to select the suitable reference genes for different life-history stages(tetrasporophyte,carposporophyte,and male/female gametophyte)of Gracilaria vermiculophylla by absolute quantitative method.Softwares geNorm and BestKeeper were used to verify the results acquired from copy number analysis.Results show that the expression of identified reference genes varied in comparing groups composed of different type of life stages.It is suggested that 18S rDNA and TubB could be used for highly complex samples composed of mixed ploidy and phases.18S rDNA and 28S rDNA were also preferred for using among the matured isomorphic samples.But for samples with different maturities,TubB and ACT were recommended for tetrasporophytes and gametophytes respectively.

Comparison and phylogeny on mitochondrial genome of marine and freshwater taxa of genus Hildenbrandia(Florideophyceae,Rhodophyta)

Hildenbrandia is an early diverged lineage in Florideophyceae,Rhodophyta.The species diversity of this genus is still unresolved due to the simple morphology and limited molecular information.The mitochondrial genome of freshwater H.jigongshanensis was determined in this study.The freshwater H.jigongshanensis had a larger mitochondrial genome than the marine H.rubra and GC content was higher.Collinear alignment structure was observed between the mitochondrial genomes of H.jigongshanensis and H.rubra,except for one block that was encoded on the complement strand.More introns were found in mitochondrial genome of H.jigongshanensis than in H.rubra,and H.jigongshanensis shares the common feature with Bangiophyceae that two introns were distributed in cox1.Comparison of mitochondrial genome organization suggests that H.jigongshanensis preserves characters that could be hypothetically more similar to the ancestor of Bangiophyceae and Florideophyceae,which differ with previous studies based on chloroplast,and nuclear markers.More mitochondrial genomes and phylogenetic analyses combing nuclear,chloroplast and mitochondrial genomes are needed to clarify this discrepancy.Mitochondrion-based phylogeny in this study resulted in better solution at both the deep and recent derived nodes than single-gene phylogenies.Most protein-coding genes between H.jigongshanensis and H.rubra were identical except atp8,which was present in H.jigongshanensis while absent from H.rubra.This finding follows the trend that high Ka/Ks ratio genes are more frequently lost than low Ka/Ks ratio ones in red algae.

Hexadecanoic acid-enriched extract of Halymenia durvillei induces apoptotic and autophagic death of human triple-negative breast cancer cells by upregulating ER stress

Objective:To investigate the effect of the hexane solvent fraction of Halymenia durvillei(HDHE)on triple-negative breast cancer.Methods:The phytochemical profile of HDHE was investigated by GC-MS.The cytotoxicity of HDHE against MDA-MB-231 cells was determined.The apoptotic and autophagic effects of HDHE were analyzed.The expression of molecular markers controlling apoptosis,autophagy,DNA damage,and endoplasmic reticulum(ER)stress was determined.Results:HDHE contains a mixture of fatty acids,mainly hexadecanoic acid.HDHE at a cytotoxic concentration induced apoptotic death of MDA-MB-231 cells through mitochondrial membrane dysfunction,and induction of apoptosis markers,and increased the expression of proteins related to DNA damage response.HDHE also induced the expression of LC-3,a marker of autophagic cell death at a cytotoxic concentration.Moreover,HDHE modulated the expression of ER stress genes.Conclusions:The hexadecanoic acid-enriched extract of Halymenia durvillei promotes apoptosis and autophagy of human triple-negative breast cancer cells.This extract may be further explored as an anticancer agent for triple-negative breast cancer.

Three new species of Batrachospermum Roth (Batrachosper-maceae,Rhodophyta) in China

Three new species of Batrachospermum Roth (Batrachospermales, Rhodophyta) from China are described in this paper. B. yunnanense sp. nov. has long-cylindrical trichogynes with long stalks and is diagnostic of section Virescentia. Within this section, B. yunnanense is similar to B. helminthosum Bory emend. Sheath et al., but it is dioecious and has curved carpogonial branches, while the latter is monoecious and has straight carpogonial branches. It is also similar to B. transtaganum Reis, but it differs from the latter in long carpogonia, big carposporophytes and carposporangia. It is considered that B. nothocladoideum sp. nov. is assigned to section Contorta, subsection Kushiroense, because its carpogonial branches are twisted and gonimoblast filaments are loosely agglomerated. This new species similar to B. iriomotense Kumano, but with short fascicles, long-ovoid or subpyriform cells, numerous terminal hairs, long-ellipsoid trichogynes, big carposporophytes and small carpo- sporangia. The plant is quite tough and cartilaginous and similar to Nothocladus in gross morphology, but its carposporophytes are compact instead of diffuse. This shows that it may be a transitional species between section Contorta and genus Nothocladus. So, B. transitorium sp. nov. should belong to section Contorta, subsection Kushiroense, because of its curved or twisted carpogonial branches and loosely agglomerated gonimoblast filaments, with globose or subglobose cells in fascicles similar to B. spermatiophorum Vis et Sheath, but no colourless spermatiophores. In terms of small and numerous carposporophytes, B. transitorium sp. nov. is similar to some species of section Batrachospermum. However, their other features are unique, indicating its transitional nature between section Contorta and Batrachospermum.

Primary species recognition and phylogeny of Chondrus (Gigartinales, Rhodophyta) using 18S rDNA sequence data

The nuclear-encoded small subunit ribosomal RNA gene （18S rDNA） of 16 isolates of Chondrus from 8 countries were sequenced. A total of 1796 nucleotides were obtained and aligned with the phylogenetic analysis conducted. The results suggest that the entity from Dalian, China, regarded as C. spl is C. pinnulatus. The C. sp2 previously depicted as C. yendoi or Mazzaellajaponica may belong to genus Chondrus. So, 4 Chondrus species, i.e.C. ocellatus, C. nipponicus, C. armatus, and C. pinnulatus are distributed in China. However, the entity from Connemara, Ireland, named C. crispus, is not a Chondrus species but that ofMastocarpus stellatus, although it is morphologically similar to C. crispus. Phylogenetic analysis based on complete 18S rDNA sequence data shows that genus Chondrus includes 3 main lineages： the Northern Pacific lineage, containing C. ocellatus, C. yendoi, and C, nipponicus; C, armatus, and C. pinnulatus form the sub-North Pacific lineage; and the Northern Atlantic Ocean lineage, comprising samples of C. crispus from Canada, Portugal, Ireland, Germany and France. The phylogenetic relationships indicate that genus Chondrus might have a North Pacific ancestral origin, radiated to North Atlantic area, and then formed the species C. crispus.